While there is ample evidence that income inequalities influence individuals’ health status, the mechanisms behind this income inequality–health correlation are only partially understood. This study shows that inequalities evaluated on the basis of individual perceptions of injustice are a driving force behind this connection. Two main questions are addressed: Does perceiving one’s earnings as unfair affect physical health? Do such perceptions contribute to structural health inequalities? The hypotheses presented are based on the effort–reward imbalance model, according to which experiencing injustice causes stress, which can have a negative effect on individual health. Analyses of large-scale longitudinal data from the German Socio-Economic Panel of the years 2005–2010 show that female employees who perceive their earnings as unjustly low display significantly worse physical health, and that if employees perceive their earnings to be unjust for an extended period, this contributes to the deterioration of individual physical health in male and female employees. Employees from lower social classes, in particular unskilled blue-collar workers, more frequently perceive their earnings to be unjust. Experience of unjust earnings mediates the relationship between social class and physical health, if to a limited extent. Our conclusion is that differential exposure to unjust earnings contributes to the emergence of structural health inequalities.